Method for producting motor fuels



May 9, 1939.

c. R. WAGNER METHOD FOR PRODUCING MOTOR FUELS 'Filed April yL21, 1953gmc/wm 762737 1 'Vl/'agiter i Patented May 9, 1939 UNITED STATES2,157,224 METHOD FOR. PRODUCING MOTOR FUELSv Cary R. Wagner, Chicago,Ill., assignor to The Pure Oil Company, Chicago, Ill., a corporation ofOhio Application April 21, 1933, Serial No. 667,255

8 Claims.

This invention relates to an improved system for producing hydrocarbonmotor fuels of the type which contain high percentages of nnsaturatedhydrocarbons and, more particularly,

the invention has to do with the treatment of unsaturated hydrocarbongases, especially those obtained from vapor phase cracking systems,whereby a large proportion of such gases are, when subjected tocontrolled conditions of temperature and pressure, transformed intohydrocarbon compounds, liquid at normal temperatures and pressures, andwhich may be used as improved motor fuels.

I'his invention is a continuation in part of the ldisclosures containedin my prior application, Serial No. 573,233 filed Nov. 5, 1931, whichhas matured into PatentI No. 2,088,886, granted August 3,1931.

It is a primary object of the present invention l to subject crackedhydrocarbon gases containing ethylene and its homologues to conditionsof elevated temperature and pressure to polymerize such gases, in part,into hydrocarbons of higher molecular weights and to accomplish thisresult l in such manner as to provide for an increased yield of the morevaluable liquid products with an accompanying decrease in the unusablepermanent gas production.

Fora'further understanding of the invention,

30 reference is to be had to the following description and theaccompanying drawing, wherein:

'Ihe ligure is a diagrammatic view illustrating the apparatus which maybe employed in carrying the present invention into ellect.

:i It will be understood that the apparatus has been butdiagrammatically illustrated in order to serve as a flow chart and thatthe positional order and elevations of the apparatus illustrated is notnecessarily that which may be used in comvMl mercial operations. i

Referring more particularly to the drawing, the

l charging hydrocarbon gas which may be of an oleflnic character andobtained, for example, from the gas separator (not shown) of a vapor 45phase oil cracking system, is passed under ordinary flowing :pressuresof the order of pounds through a pipe line I for delivery to the lowpressure cylinder 2 of a two-stage compressor C. After being compressedin the cylinder 2 to 50 a pressure of the order of 250 pounds per squareinch. the gas is forced through a pipe line 3, and

a heat exchanger 4 to a gas separator 5. In this separator there takesplace the separation of the more readily liqueiiable constituents of thecharging gas from the remaining compounds (on. 19o-s) which do not formliquids under the pressures specied.

The substantially liqueed compounds are removed from the bottom of theseparator 5 and, without any substantial release of pressure theren on,are passed to a stabilizing or fractionating column 6 through theconnecting pipe line l, the latter leading from the bottom of theseparator 5 to a point substantially intermediate of the height of thecolumn 6. This column may be provided with the usual internally situatedbaiiles or trays 8, or other standard liquid and vapor contact means,whereby low boiling compounds entrained in the oils delivered to thecolumn 6, and present as vapors, may be brought into intimatecounter-current contact with the higher boiling liquid compounds. Thosecompounds which accumulate in the bottom of the column 6 as stabilizedliquids are withdrawn either continuously or intermittently through thevalved draw-oil line' and'possess the boiling range of gasoline. Theseoils may be-referred toas the polymerized distillate and due to the highpercentage of unsaturated hydrocarbons which they contain, may be useddirectly as an anti-knock motor fuel, or as a blending oil forincreasing the anti-detonating value of a lower grade motor fuel oil.

The remaining vapors or gases are withdrawn from' adjacent the top ofthe column 6 and are passed through a pipe line I0 to a suitable ccnldenser II, and thence to a separating chamber I2 in which a variablepressure usually not in excess of 250`p'ounds is maintained. Permanentgas is removed from the top of the chamber I2 through the valved gasoutlet line I3, while the condenser cooled liquid fraction is withdrawnfrom the bottom of said chamber through the pipe line I4 and deliveredto the suction side of a pump I5. A pipe line I6 leads from the Voutletside of said pump to a heating -coil I1 located in a pipe still I8, thelatter being provided with the customary burners I8. Alsoleading fromthe pipe line I6 is a branch I9, which extends to the top of the column6 to provide for the passage of a reflux oil downwardly through saidcolumn to control the fractionation taking place therein. The gasesremoved from the primary separator 5 by way of the top line 20 arepassed to the high pressure cylinder 2| of the compressor C, wherein thepressure of the gas is'increased from approximately 250 pounds to aconsiderably higher pressureof the order of 500 to .2000 pounds persquare inch, and under thislatter pressure, the gases aredelivered tothe line I6 leading to the heating coil I1, a connecting pipe line 22being employed for this purpose.

Naphtha obtained from topping plants or the `like may be introduced intothe system by way forming of naphtha into a low boiling motor fuel oilcontaining high percentages of unsaturates. Thus the general utility ofthe present system is materially increased by its ability to reformnaphtha without requiring additional refinery equipment for effectingthis increasingly important operation. In the coil I1, the gases alone,or a mixture of the gases and liquids, are heated to temperatures oi'the order of 850 F. to 1100 F. while maintained under' superatmospherlcpressures varying between 500 to 2000 pounds per square inch. The systemoperates quite satisfactorily, however, when the products dischargedfrom the coil I1 possess a temperature of the order of 950 F. to 1000 F.and a. pressure oi about 700 pounds.

These products are then transferred to an externally disposed Areactiondrum 24, which is preferably unheated from external sources, althoughthe metallic drum maybe covered by a suitable heat insulating materialif desired. 'I'he drum 24 may be lined with silica or ganister, ifdesired, to avoid catalytic dehydrogenation in some cases. Since thepolymerizing reactions which are eifected in the zone 24 are highlyexothermic in character, care must be exercised to prevent the reactioncompounds from attaining undesirably high temperatures, such as 1100 F.to 1200 F., since such high temperatures tend to crack or decompose thecompounds, thereby causing excessive fixed gas formation and markedreduction in the recovery of the desired liquid products and alsoundesirable coke formation. Suitable pressure and temperature recordinginstruments 24` may be employed in connection With the reaction drum, asin other parts of the system, to enable an operator to exercise accuratecontrol over the functioning thereof, The temperature of the productswithin said drum is preferably maintained at substantially 950 F. tol025 F., together with pressures of the order of 600 pounds per squareinch.

Further, regulation of the temperature in the polymerization zone, whichincludes the reaction drum 24 may be effected by regulating theintroduction of naphtha into the polymerizing zone. Thus naphtha may beadded in such quantities so that the endothermic heat of the reactionsinvolved in cracking or reforming naphtha approximately balances theexothermic heat produced by the polymerizing of oleflns. In this mannereffective control of reaction-producing temperatures in the polymerizingzone is obtained.

Following the completion of the desired reactions in the drum 24, theheated products are then passed through'a pipe line 25 toa cooler orheat exchanger 26 and thence to a final separator 21; 'Ihis separator ismaintained under a variable pressure, but usually one of the order of450 pounds. The fixed gas may be withdrawn from the separator 21 by wayof the overhead valved line 28 and removed frpm the system for storageor other suitable use, While the liquid fraction is withdrawn from thebottom of the separator and transferred by way of the pipe line 29,containing the 'pump 30, and delivered to the pipe line 3 for passagethrough the heat exchanger 4, the gas separator 5 and the stabilizingcolumn 6. A branch pipe line 3| may be employed to divert a part of theliquid passing through the line 29 to a jet cooler 32 disposed in thepipe line 25 at the outlet of the reaction drum 24, whereby accuratecontrol is obtained of the temperature of the products delivered to theseparator 21, insuring condensation of all normal liquid-like productstogether with minimum formation of carbon deposit, the productsdischarged from the drum 24 being shock chilled to nonreactingtemperatures in a very short interval of time.

The present system provides for a very high recovery of liquid oils ofmotor fuel boiling'range from cracked refinery gases or otheroleflne-containing gases. It will be noted that waste or fixed gas may,be withdrawn optionally through the lines I3 and 28, insuring acomplete elimination of those gaseous compounds which do not polymerizeand, conversely, the system provides for the subjection in a sustainedmanner of all hydrocarbons which under the conditions of temperaturean'd pressure specified tend to polymerize into higher boilinghydrocarbons, thus effecting the formation and recovery of a maximumquantity of liquid oils or motor fuels from a given amount of charginggas.

What is claimed is:

1. In a process of producing motor fuel of high anti-knock rating whichcomprises mixing gas having an olefin content sufliciently high to reactexothermically with rise in temperature and a hydrocarbonr oil whichreacts endothermically under the conditions to which the mixture issubjected, heating the mixture to a temperature of the order of 850 to1100? F. under pressures of from 500 to 2000 pounds per square inch, andmaintaining the mixture Within the reacting temperature range for aperiod of time suiiicient to bring about the desired conversion, thestep which consists in proportioning the gas and oil in such quantitiesthat the heat liberated by the reactionV of the gas is substantiallybalanced by the heat absorbed by the reaction of the oil.

2.'In a process of simultaneously reforming naphtha and polymerizingolefin containing gases to liquid hydrocarbons which comprises heating amixture of 'said gases and naphtha in a restricted stream sufficient toenable the mixture to attain a temperature of from 850 to 1100 F. un-

der a pressure above 500 pounds per square inch but not substantially inexcess of 2000 pounds yper square inch, passing the heated mixture intoan enlarged reaction zone Without substantial reduction in pressure, andmaintaining said mixture in said zone for a period of time suiicient toconvert a substantial portion of olefinic gases to liquid hydrocarbonsof gasoline boiling range, the step which consists in proportioning thegases and naphtha in the mixed stream subjected to heating andpolymerization in such quantities that the heat evolved by theexothermic polymerization of the gases substantially balances the heatabsorbed by the endothermic reforming of the naphtha.

3. In a process for simultaneously reforming naphtha and polymerizingolefin containing gases to liquid hydrocarbons which comprises heating amixture of said gases and naphtha in a restricted stream, and passingthe heated mixture into an enlarged reaction zone wherein the mixture ismaintained under pressures of from 500 to 2000 pounds per square inchtand at temperatures of 850 to 1100 F. for a period of time sumcient toconvert a substantial portion of oleflnlc gases to liquid hydrocarbonsof gasoline boiling range, the step which consists in adding additionalquantities of naphtha to the reaction zone in such amounts that the heatabsorbed by the endothermic reaction of the naphtha' will substantially.balance the heat liberated by the exothermic reaction of the gases. y

4. The process for converting oleflnic gaseous hydrocarbons to normallyliquid hydrocarbons which comprises. heating said gases to a temperaturesufficient to initiate exotherrnic polymerization of the gases whilemaintained under super-atmospheric pressure, maintaining the heatedgases in a.' polymerization zone under temperatures and pressuressufficient to convertk a substantial portion of the gases to normallyliquid hydrocarbons, and regulating the temperature in thepolymerization zone by introducing polymerization of said gases andmaintaining the mixture at such temperatures and pressures for a periodof time sumcient .to convert a substantial portion of said gases toliquid hydrocarbons, the step which consists in proportioning the gasesvandnaphtha in the mixed stream subjected to heating and polymerizationin such quantities that the heat evolved by the exothermicpolymerization of the gases substantially balances the heat absorbed bythe endothermic reforming of the naphtha.

7. The process of simultaneously polymerizing hydrocarbon gases rich inolens and reforming hydrocarbon oil which comprises heating a mixture ofsaid gases and hydrocarbon oil under high superatmospheric pressure to atemperature suitable for polymerization of said gases,.main taining themixture in an unheated polymerization zone at such temperature andpressure for a period of time sufiicient to convert a substantialportion of said gases to liquid hydrocarbons. and adding furtherquantities of hydrocarbony oil to the reaction products in the reactionzone in amounts sufcient to prevent excessive temperature rise but ininsuiilcient amounts to effect material lowering of the temperature.

8. The process of simultaneously polymerizing hydrocarbon gases rich inolens and reforming naphtha which comprises heating a mixture of saidgases and naphtha under high super-atmospheric pressure to a temperaturesuitable for polymerization of said gases, maintaining the mixture in anunheated polymerization zone at such temperature and pressure for aperiodoi' time suilicient to convert a substantial portion of said gasesto liquid hydrocarbons, and adding further' quantities of naphtha to thereaction products in the reaction zonein amounts sumcient to preventexcessive temperature rise but ln insufficient amounts to effect,material lower- 35 ing ofthe temperature.

CARY R. WAGNER.

